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ON-SITE WASTE DISPOSAL SYSTEMS

Types, Design, Inspection - Septic Systems

NY Metro Annual Seminar -Two Hours - September 11, 2010Daniel Friedman, Approved NYS Instructor - InspectAPedia.com ®Original course outline: by Victor Faggella – NY Metro ASHI

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Septic System Info-Live

• Handouts http://inspectapedia.com/septic/Septic_Systems_Class_DF_Handouts.pdf

• Text http://inspectapedia.com/septic/Septic_Systems_Class_DF_VF.pdf

• The Septic Systems Information Website

http://inspectapedia.com/septbook.htm• dfriedman at inspect-ny.com

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SEPTIC SYSTEM SAFETY WARNINGS

• Collapse

• Infection

• Explosion

• Asphyxiation

• Prevent access, issue warnings, keep out

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Wastewater Basics

• Blackwater – toilets

• Graywater – other fixtures

• Wastewater – metals, pathogens, salts

• Biomat – bacteria/fungi around leachline

• Septic tank – retains solids, 45% treatment

• Absorption system – treat & dispose of effluent, remaining treatment to 95%

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Wastewater Basics

• Disposal – get rid of effluent– Discharge to soils– Evaporate to air

• Treatment – biological process to make effluent sanitary before discharge to environment

• Disinfection - chemical process to make effluent sanitary before discharge

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Basic Designs - Cesspools

• Dug pit, old=site built (block, stone) or modern=pre-cast concrete, accept blackwater

• May be the only system • May be accompanied by drywells (graywater) • Only liquids permeate soil• Solids require frequent removal• Periodic relocation required• Old property = string of “extended” cesspools

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Cesspools Failures & Deaths

• Site built, risk of collapse, fatality (L.I.)

• Cannot adequately treat septic effluent (too deep, low oxygen)

• Failure criteria: waste within 12” of inlet; less than ½ days storage; too close to surface water; too close to well

• Cesspool restorers??

• Cesspool pumping? Can cause collapse.

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Cesspool Sinkhole

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Basic Designs: Seepage Pits

• Dug pit like a cesspool BUT

• Work with an existing septic tank

• Used when insufficient space for a drainfield

• Cannot adequately treat septic effluent (too deep, low oxygen)

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Seepage Pits

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Basic Designs - Drywells

• Hand or machine dug pit for graywater, roof drainage &c• W/ conventional tank & drainfield = clue about limited

drainfield • Reduces load on drainfield• Extend life with input filter• Drywells not “dry” in areas of seasonal wet soils or

flooding

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Better Cesspools, Seepage Pits, Drywells

• Machine dug

• Gravel under & around

• Pre-cast concrete forms or rings (reduced collapse risk)

• Concrete cover

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Basic Designs: Septic Tank & Field

• Septic Tank Materials– Steel: 5-15 years, rustout, lost baffles,

infection, collapse, unsafe covers– Concrete: long life, spalling, leaks-in?– Plastic/fiberglass: long life, float-up– Site-built: block, stone, brick: unsafe– Wood: no life

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Basic Designs: Septic Tank Sizes

• 250 gal & 500 gal = obsolete, inadequate, not permitted

• 1000g to 5000g• Size needed based on daily wastewater flow• Net free area: subtract scum & sludge• Settlement time depends on net free area size &

system usage – incoming wastewater volume & frequency

• Too-small net free area sends solids into drainfield – reduced field life

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Basics: Tank Compartments

• Single compartment + baffles

• 2-Compartments – Improved separation of solids– Increased net free area– Longer drainfield life– Improved effluent treatment– Required for some designs (aerobic)

• 3+ - aerobics, clarifying, pumping

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Septic Tank Compartments

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Basics: D-Boxes

• Distribution box = junction box = drop box

• Connect tank to field lines

• Fan systems: multiple D-boxes

• Defects (dig up, open)– Tipped– Flooded– Adjust flow balancers– Sewage present

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D-Boxes

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Basics: Drainfields

• Drainfield = leach field = soakaway bed = drainage bed = septic field = gravel trench = galley system etc.

• 4” Perforated pipe in gravel-filled trenches holes “down” at 5 & 7 o’clock

• 2ft – 5ft deep, 8” – 36” wide, 6’ spacing+• Length depends on soil percolation &

wastewater flow • Inspection ports? • Gravelless – no-rock: plastic galleys, wider,

shorter

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Drainfield vs Water Table

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Advanced / Alternative Septic Designs (examples not discussed)

Evaporation Transpiration, Filters, Greywater, Hoot, Dropbox & Media Filters

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SEPTIC SYSTEM DESIGN ALTERNATIVES http://inspectapedia.com/septic/septalts.htm

AEROBIC SEPTIC SYSTEMS http://inspectapedia.com/septic/altaerobic.htm

ALTERNATING BED SEPTIC SYSTEMS http://inspectapedia.com/septic/Alternating_Bed_Septic.htm

BIOGAS PRODUCTION & USE http://inspectapedia.com/heat/Biogas_Production.htm

CESSPOOLS http://inspectapedia.com/septic/septcesspools.htm

DISINFECTION SYSTEMS, SEPTIC EFFLUENT http://inspectapedia.com/septic/Effluent_Disinfection_Septic.htm

DRYWELL DESIGN & USES http://inspectapedia.com/septic/septdrywell.htm

EVAPORATION-TRANSPIRATION SEPTIC SYSTEMS http://inspectapedia.com/septic/altevaptrans.htm

FILTERS SEPTIC & GREYWATER http://inspectapedia.com/septic/septicfilters.htm

FIXED-FILM PROCESS SEPTIC SYSTEMS http://inspectapedia.com/septic/Fixed_Film_Septic.htm

GRAVELLESS SEPTIC SYSTEMS http://inspectapedia.com/septic/gravelless.htm

GRAVITY/SIPHON DOSING SYSTEMS http://inspectapedia.com/septic/altgravitydose.htm

GREYWATER SYSTEMS http://inspectapedia.com/septic/altgreywater.htm

LAGOON SEPTIC SYSTEMS http://inspectapedia.com/septic/Lagoons.htm

MEDIA FILTER SEPTIC SYSTEMS http://inspectapedia.com/septic/altmedia.htm

MOUND SEPTIC SYSTEMS http://inspectapedia.com/septic/altmound.htm

OUTHOUSES & LATRINES http://inspectapedia.com/septic/Outhouse_Latrine.htm

PRESSURE DOSING SEPTIC SYSTEMS http://inspectapedia.com/septic/altpressuredose.htm

RAISED BED SEPTIC SYSTEMS http://inspectapedia.com/septic/altraised.htm

SAND BED SEPTIC SYSTEMS http://inspectapedia.com/septic/altsandbed.htm

SEEPAGE PITS http://inspectapedia.com/septic/Seepage_Pits.htm

SEPTIC SYSTEM PUMPS http://inspectapedia.com/septic/SepticPumps.htm

SEQUENCING BATCH SEPTIC SYSTEMS http://inspectapedia.com/septic/Sequencing_Batch_Septic.htm

SEWAGE TREATMENT SYSTEMS http://inspectapedia.com/septic/sewagetreat.htm

TOILET ALTERNATIVES http://inspectapedia.com/septic/waterless.htm

TOILET TYPES http://inspectapedia.com/plumbing/Toilet_Types.htm

TRAPS on PLUMBING FIXTURES http://inspectapedia.com/plumbing/Plumbing_Fixture_Traps.htm

VEGETATED SUBMERGED SEPTIC BEDS http://inspectapedia.com/septic/Submerged_Septic_Beds.htm

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Aerobic Septic Systems ATUs• Septic tank aerator (pump, electrical power), pre-

packaged / retrofit• 3 chamber tank (trash tank, aeration, clarification

chamber)• 4 chamber tank (sewage receiver, aeration, settling,

pumping) • High level of treatment (to 95%)• Effluent dispersed conventionally or by surface spray • Suspended-growth (dead bacteria suspended) vs

Attached-growth (fabric media)• AKA saturated wastewater treatment system (oxygen-

saturated wastewater)• Retrofit aerobics promise drainfield rejuvenation

(doubtful in short term & possible issue with single-chamber tanks)

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Vic’s Alternating Bed Septics

• Used when field area is limited with no room for expansion

• Field life is prolonged due to resting periods

• May be either gravity fed or a dosing system

• Required diverter valve may be either manual (coffee cup) or automatic

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Alternating Bed Septic System - automated

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Dosing Septic Systems

• Uphill sites

• Mounded systems

• Longer field life due to resting periods

• Allows system on otherwise unusable sites (nearby lake, rock, mound needed)

• More expensive to install and maintain; more complex tank, pump, alarm

• Require electrical power

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Dosing: Gravity

• Effluent lines: single, multi, serial, looped

• Float Control

• Tipping or Dipping Control

• Bell Siphon Control

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Bell Siphons

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Drip / Irrigation Septics

• Used when there is lack of earth surface over bedrock

• Landscaping concerns• Small perforated tubing slowly emits wastewater

through a system of electronics and valves through small disposal tubing

• Provides water for lawns and plants• Requires annual pumping and filter cleaning to

prevent clogging of tubing Perforations

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Drip Irrigation

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Gravelless / No-Rock Septics

• 3 Common designs– Chambers: Plastic chambers in series, set in soil with no gravel– Polystyrene-wrapped perforated pipe– Geotextile wrapped perforated pipe

• Cheaper, faster, more profitable for installers (but wider excavation)

• Wide footprint to obtain absorption area• Shorter length, may fit on smaller site than gravel-trench

system, but up to 100’• Used on rolling land, uneven slopes?• Life expectancy: TBD.

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Gravelless Septic Layout

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Mound Septic Systems

Peat Mound

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Mound vs Raised Bed

• Raised bed: soil fill atop natural soil, both treat & absorb

• Mound: fill over rock or non-usable soil

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Sand Bed Septic Systems

• Sand “mound” or bed, may use a dosing system• Sand covered with soil may not be obvious• Intermittent Sand Bed – intermittent distribution• Recirculating sand bed – recirculates through the sand

back to tank etc. • Disinfection system common as final treatment • Direct discharge of effluent to a body of water is not

approved (but common) • Expensive to maintain, re-rake sand; rarely properly

maintained• Alternative design may be required at time of

replacement or major repair

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BREAK TIME

FIVE MINUTES

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Septic Inspection & Testing

• Options: No inspection – warn of visually apparent hazards, advise expert inspection, not just tank pumping

• I - Visual inspection

• II - Visual + loading & dye test

• IV - Visual, loading & dye, Tank Pump

• V - Visual, loading & dye, pumout, D-box, Field exploration

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Septic Inspection Worries

• Septic Inspection Safety – Avoid fatalities & explosions– Never fail to warn, restrict access &c

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Visual Warnings

• Subsidence – rope off and prevent near access

• Steel tanks – old, rust, collapse risk

• Unsafe, missing covers – rope off, prevent access

• Obvious site limitations

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Smell Warnings

• Bacterial hazards

• Explosion hazards

• Methane gas asphyxiation hazards – don’t lean over and never enter a septic tank

• No Smoking, no brush fires

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Information Warnings

• Cesspools – old, site built, high risk of collapse, do not water-jet, pump out, agitate (Long Island fatality case)

• Old properties, possible series of tanks, cesspools, improperly abandoned? Later collapses.

• Location unknown• No service record• Pumped before inspection• Bleach (well shocking) • Sinkholes?

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What Can be Detected?

• Collapse, visible subsidence• Smells, operation problems• Drainfield failures: wet, odor, growth, context:

too small, old, flooded area, unknown, no maintenance, lost baffles, paved over, driven over, deck over, house over

• Tank failures (open tank): baffles, leaks in, leaks out, too small, site built, unsafe cover, impacted,

• Wet around pipes, tank, field

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How to Inspect a Septic

• Collect Historical Information about the Onsite Waste Disposal System

• Visual Site Inspection of the Septic System:• Locate the Septic System• Performing Septic Loading & Dye Tests• Pumping Septic Tanks for Further Investigation

of System Condition• Excavating & Inspecting Septic Distribution

Boxes• Inspecting the Soil Absorption System of an

Onsite Wastewater Disposal System

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Septic History

• Where is the septic tank

• Where is the drainfield

• What type, size, materials were used (concrete, steel, plastic, etc)

• What is the maintenance history of the system

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Visual Inspection

• Possible component locations• Unlikely locations• In-building waste piping

– Exit points – indicate direction piping leaves building– History – conversion from septic to municipal – old

system abandoned?– Multiple exits – multiple tanks, drywells, seepage pits– Evidence of backups, burst pipes, sewage

contamination– Do not run water for a dye test without also checking

immediately for in-building leaks or backups

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Initial Outside Septic Checks

– Storm drains– Open bodies of water, stream, lake, etc

(check again with dye) – Location of well– Property boundaries– Roads, culverts (effluent piped under roads)– Location of the flood plain– High water tables that may flood the drainfield

– Algae growth in nearby water

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Find the Septic Tank

• Walk the known or most likely septic tank area– Subsidence– Evidence of recent

work (tire tracks, excavation, pump out just before inspection)

– Wet areas

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Mini septic tank, pump, dye, realtor

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Find the Drainfield

• Walk the known or most likely septic field area – Excessive grass growth

– Wet or “boggy” areas

– “Collapsing” fields

– Odor

– Evidence of recent work

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Septic Loading & Dye Test

• Definitely finds some problems• Definitely does not find all problems• Value: risk reduction, not risk

elimination• Watch out:

– no tank pumping before– Owner permission– Don’t spill dye

(flush the toilet first)– Use enough dye & water– Put the dye in the right fixture

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Septic Dye Breakouts

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Septic Dye Breakout

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Septic Dye Test Lawsuit

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Effluent loading breakout, no dye

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Dye Test Inspection Points

• Building DWV before starting test

• Toilet flushes ok before starting test

• Presence of a drywell (laundry sink?)

• Follow fixture piping to main DWV to exit

• Outside waterways: immediately on test start & periodically

• Probe? Wet areas for increased flooding over seen before starting test

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Septic Test Inspection Points

• Check tank alarms if present

• Monitor & compute flow quantity

• Watch for well run-dry

• Stop test immediately on overflow, breakout, ejector pump failure, owner request

• Check drainfield inspection ports

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Septic Tank Pumpout Inspection

• After loading & dye test

• Not part of loading/dye test

• Useful but incomplete if done without loading & dye test (fields not checked)

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Septic Tank Inspection Points

– Septic tank location & thus maintenance history– Septic tank cover material, condition, safety– Tank materials & condition – Effluent level (leaks in to or out of tank?)– Condition of baffles, lost, broken, overflowed– Measure scum and sludge thickness– Evidence of groundwater entering/flooding the tank– Effluent pump or backup pump not working– Tank alarm not working– Septic tank cracks, holes, rust-out – Dosing siphons not working – Backflow from outlet pipe (to fields) during pumping?

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Septic Tank Pumpout Inspection

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Septic D-box Inspection

– Septic tank location & thus maintenance history– Septic tank cover material, condition, safety– Tank materials & condition– Effluent level (leaks in tank?)– Condition of baffles– Measure scum and sludge thickness– Evidence of groundwater entering/flooding the

tank– Effluent pump or backup pump not working– Tank alarm not working– Septic tank cracks, holes, rust-out – Dosing siphons not working

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D-Box interior trouble

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Septic Maintenance

• Pump the septic tank on schedule

• Use a standard schedule or

• Open, inspect, measure scum & sludge levels & pump per specs

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When to Pump the Septic Tank

• Use the pumping freq. table• 2-4 years on average• When 400mm scum or 200mm sludge• When scum + sludge = 1/3 of tank depth• Less than 3” from outlet tee to scum bottom• Less than 6” from outlet tee to sludge top (late?)• 20% to 40% More often if Garbage Grinder• 95% of failures blamed on failure to pump

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Don’t Flush

• Grease, garbage, sanitary napkins, baby wipes, toys, cat litter, condoms

• Solvents, paints, chemicals, drugs

• Additives and magic septic restorers, potions

• Cats

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Keep Off of Drainfields

• Trees, deep-rooting plants

• Grazing Land & livestock

• Paving, patio blocks

• Vehicles

• Parking lots, roads

• Buildings

• Swimming Pools

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Septic System Info Live

• The Septic Systems Information Website http://inspectapedia.com/septbook.htm

• dfriedman at inspect-ny.com

• 914-489-1635 – home inspectors ONLY